Using the same picture, draw a line starting at the prosternum through your dog's body.

What is the prosternum? It is that "pointy thing" at the front of your dog's chest. The prosternum is the tip of the bone to which the ribs attach.

You should be able to actually grasp the prosternum with your fingers. According to Pat Hastings, "Since a good prosternum surface is necessary for proper muscle attachment, which links the upper arm to the ribcage, a lack of prosternum may result in a very loose forward motion..."

Make sure your picture is taken as level with your dog as possible. This pup shows the perfect "prosternum line" you want. One half of the dog's body is above the line, and one half is below. Pups should be evaluated at 8 weeks of age, or wait until the dog is about 12 months. However, serious faults will show up at any age.

This is what you want to see. The body bisected in half.

This dog's body is primarily above the line.

If the prosternum is low on the body, the dog has a short upper arm. If the prosternum is high on the body, the dog's upper arm is too long and/or the scapula is too short. Pat Hastings: Tricks of the Trade

This overweight nine year old dog shows a decent prosternum line; it is a touch low, which goes along with the slightly short upper arm.